Apparatus for feeding fibers



May 28, 1968 J. N. HELMS APPARATUS FOR FEEDING FIBERS Filed July 13, 1966 FIG.Z

FIG. I'

R o m 1 m a 2 m. 1 N Y m 6 I 2 u ll l infl n. E 0 u u ow 0 MN 0 w I United States Patent 3,385,491 APPARATUS FOR FEEDING FIBERS Jerry N. Helms, Kinston, N.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed July 13, 1966, Ser. No. 564,853 2 Claims. (Cl. 226--25) This invention relates to apparatus for the cutting of crimped continuous-filament tow and more specifically to tension-control apparatus by means of which improved control of cut-lengths may be accomplished.

In the textile processing of staple, it is necessary to good continuity of the operations, and to the uniformity of the resulting yarns, that the staple be crimped to an appropriate degree. In the production of synthetic fiber for staple end-uses, the crimp is imposed on the fiber while it is in a continuous-filament state. Only by this means can a relatively uniform amount of crimp be developed in all filaments. The presence of crimp prior to cutting of such continuous-filament structures creates problems in regulation of cut-lengths. The application of sufficient tension to straighten the crimped fibers during fiber metering will, in some cases, result in an unacceptable degree of permanent crimp-loss in the final product. It is characteristic of some cutters, furthermore, that tension applied to the fiber during metering must be released just before the cut is made. It also is not feasible to control the crimping operation to such high precision that a given amount of tension, necessarily less than that which will completely straighten the fiber, will always result in the same crimp removal. A means for minimizing the effect on cut-length of variations in crimp would be highly desirable.

This invention provides an improved apparatus for control of cut-lengths. It further provides both manual and automatic means for compensating lot-to-lot variations which affect cut-lengths under a given set of operating conditions. It further provides a convenient means for establishing cutter operating tensions required for different deniers and types of fibers. Additional advantages will become apparent from the drawings, description and claims.

In the drawings, which illustrate a preferred embodiment of the invention,

FIGURE 1 is a front elevation of the apparatus and FIGURE 2 is across-sectional side view taken on line 22 of FIGURE 1.

In the embodiment shown in the figures a tow is supplied at constant speed passes upward through a tension compensator unit 11, is snubbed by adjustable tension bars 12, 13, 14, 15, reverses direction around top tow-turning roll 16, passes downward to bottom tow-turning roll 17 and proceeds to a staple cutter (not shown). The above elements are supported by frame 18. The tension compensator unit comprises entrance guide roller 19, exit guide roller 29, and an intermediate guide roller 21 mounted on adjustable tension compensator shoe 22. The shoe is supported on rod 23 which slides through bearing block 24. Lever arm 25 presses against the end of the rod, swivels about support bearing 26, and supports a tension weight 27 for pushing the shoe 22 to one side. This maintains the tow under constant tension during passage to the adjustable tension bar 12. A tightline switch 28 is actuated by the lever arm to shut off tow-feeding mechanism if this tension is exceeded.

Tension bars 12 and 13 are supported by crank member 30 which is attached to axle 31 extending through the frame. The snubbing action of the bars, and hence the tension in the tow, is adjusted by turning the axle. Tension bars 14 and are similarly supported by crank member 32 attached to axle 33 for adjustment of tension. Top H tow-turning roll 16 is a free-wheeling roll arranged to drive tachometer generator 35 having an output voltage 3,385,491 Patented May 28, 1968 proportional to the speed of the tow. A knot-detector switch 36 is actuated to shut off tow-feeding mechanism it a knot in the tow passes over roll 16.

Under normal conditions of operation, it has been found that there is a linear relationship between the tow speed which results from tension adjustment and the cut-lengths which are produced by the staple cutter. Accordingly, the cut-lengths can be controlled by adjusting the tension bars in accordance with the speed indicated on tachometer scale 37. The required tension control can be accomplished by manually resetting the position of the tension bars, or the output of the generator can be used to provide an automatic control. In FIGURE 1, an automatic control 38 is indicated for axle 31 and a manual control 39 is indicated for axle 33. Conventional electrical or pneumatic means responsive to the generator output are suitable for automatic tension control. The axles 31 and 33 can be coupled together for simultaneous adjustment by a single means.

Automatic control is preferred. The control 38 is adjusted to provide an arbitrary amount of additional tension on the tow as it proceeds at standard rate through the feed and cutter mechanisms. Samples of the cut fiber are evaluated for cut-length. If it is found that the cut-length is a bit shorter than desired, control 38 is adjusted to provide, for that level of signal being generated by the tachometer generator, a somewhat lower tension; to correct a longer-than-desired cut-length, the level of tension developed for that level of signal is increased. By this trial and error procedure it is possible to calibrate the tension requirements of any given tow. Thus, knowledge of the polymer it comprises, the denier of the individual filaments, the total denier of the tow and any other pertinent variables, can be made an adequate basis for selection of a single setting of the controller for any given cut-length which will maintain automatic cut-length regulation throughout the production run. In this embodiment it is only necessary to establish with control 38 the proper relationship between the output of the tachometer generator (corresponding to the speed of roll rotation) and the position of the tension bars. The control 38 will then maintain this relationship with the changes in speed of rotation of the tachometer generator for continuing production.

The apparatus of this invention may be adapted to control cut-lengths for any given cutter. It is only necessary to establish empirically the relationships of the linear rate of tow feed at the tachometer generator, tension on the tow, and cut-length resulting with a given cutter to establish the proper tension/roll-speed ratio for that cutter. A variety of means may be employed to develop the signal which is proportional to the speed of tow travel, and it may be positioned at roll 16 or subsequently. The signal may be employed to modulate a variety of controls, for

. example, pneumatic or electronic means for development of useful power output to vary tension. It will also be apparent to one skilled in the art that a variety of means may be used to vary the tension on the yarn. The specific embodiment described employs bars over which the tow is drawn; the tension developed is a function of the angles of wrap, and the angles of wrap are varied by rotation of the assembly. An alternative is a roll around which the tow makes an appreciable wrap and which is variably braked in proportion to the signal developed by the tachometer generator. It is within the scope of this invention to develop the total tension required for cutting a given filamentary tow with one or more variable tensioning devices, with or without means for pre-tensioning of the tow. It is also within the scope of this invention to employ manual mcans to adjust tension on the tow based on ob servation of the level of signal generation and empirically based knowledge of what is proper for a given tow being cut on a given cutter.

Since a larger number of embodiments can be visualized which do not depart from the essential features of the invention as described herein, it is intended that the invention not be limited except as set forth in the appended claims.

I claim:

1. In an apparatus for feeding tow to a staple cutter under controlled tension comprising a tension compensator for maintaining a constant tension on the tow, a tow-turning roll for guiding the tensioned tow to the staple c utter and adjustable tension bars between the tension compensator and the tow-turning roll for increasing the tension on the tow; tachometer generator means for providing an output voltage proportional to the speed of the tow-turning roll, and control means for adjusting the tension bars to alter the tension on the tow in linear relationship with the output of the tachometer generator.

2. Apparatus as defined in claim 1 having automatic control means for adjusting the tension bars in accordance with the voltage output of the tachometer generator.

References Cited UNITED STATES PATENTS 3,032,245 5/1962 George et al 226l95 X 3,322,315 5/1967 Eberlin 226-195 X 3,335,928 8/1967 Angcll 226-195 ANDRES H. NIELSEN, Primary Examiner. 

1. IN AN APPARATUS FOR FEEDING TOW TO A STAPLE CUTTER UNDER CONTROLLED TENSION COMPRISING A TENSION COMPENSATOR FOR MAINTAINING A CONSTANT TENSION ON THE TOW, A TOW-TURNING ROLL FOR GUIDING THE TENSIONED TOW TO THE STAPLE CUTTER AND ADJUSTABLE TENSION BARS BETWEEN THE TENSION COMPENSATOR AND THE TOW-TURNING ROLL FOR INCREASING THE TENSION ON THE TWO; TACHOMETER GENERATOR MEANS FOR PROVIDING AN OUTPUT VOLTAGE PROPORTIONAL TO THE SPEED OF THE TOW-TURNING ROLL, AND CONTROL MEANS FOR ADJUSTING THE TENSION BARS TO ALTER THE TENSION ON THE TOW IN LINEAR RELATIONSHIP WITH THE OUTPUT OF THE TACHOMETER GENERATOR. 